Light-sensitive super-sensitized silver halide photographic emulsion

ABSTRACT

A green-sensitive supersensitizer for light-sensitive silver halide photographic emulsions comprises a combination of at least one dye represented by the formula:   WHEREIN R1 is a lower alkyl group, R2 is a sulfoalkyl group, a carboxyalkyl group or a derivative of any of said groups, W1 and W2 are individually a hydrogen atom or a lower alkyl group, Z is a sulfur or selenium atom, X is a negative group, and n is 1 or 2 and at least one dye represented by the formula:   WHEREIN R3 and R4 are individually a lower alkyl group or a substituted alkyl group, R5 and R6 are individually a lower alkyl group, a hydroxyalkyl group, a sulfoalkyl group or a derivative of any of said groups, Y1 and Y2 are individually a n-propyl, iso-propyl, n-butyl, iso-butyl or phenyl group, X is a negative group, and n is 1 or 2.

United States Patent [191.

Sato et a1.

- [11], 3,765,899 Oct. 16, 1973 LIGHT-SENSITIVE SUPER-SENSITIZED SILVER HALIDE PHOTOGRAPHIC EMULSION [75] Inventors: Shui Sato, Tokyo; Eiichi Sakamoto,

Hanno; Ylrii Watanabe, Saitama-ken; Kaiichiro Sakazume; Tokuzo Kaneko, both of Tokyo, all of Japan [73] Assignee: Konishiroku Photo Industry Co.,

- Ltd., Tokyo, Japan [22] Filed: July 11, 1972 [21] Appl. No.: 270,830

Related US. Application Data [63] Continuation-impart of Ser. No. 18,622, March 11,

1970, abandoned.

[30] Foreign Application Priority Data 3,666,480 5/1972 Shiba et a1. 96/124 3,713,835 l/1973 Sato et a1 96/124 3,718,475 2/1973 Shiba et al. 96/124 Primary Examiner.1. Travis Brown Attorney-Eric H. Waters et al.

[57] ABSTRACT A green-sensitive supersensitizer for light-sensitive sil-.

ver halidephotographic emulsions comprises acombination of at least one dye represented by the formula:

wherein R is a lower alkyl group, R is a sulfoalltyl group,-a carboxyalkyl .group or a derivative of any of said groups, W and W are individually ahydrog en atom or a lower alkyl group, Z is a sulfuror selenium atom, X is a negative group, and n is l or 2 and at least one dye represented by the formula:

wherein R and R are individually a lower alkyl group i or a substituted alkyl 'group, R and R are individually a lower alkyl group, a hydroxyalkyl group, a sulfoalkyl group or a derivative of any of said groups, Y and Y, are individually a n-propyl, iso-propyl, n-butyl, isobutyl or phenyl group, X is a negative group, and n is 1 or 2.

3 Claims, N0 Drawings LIGHT-SENSITIVE SUPER-SENSITIZED SILVER HALIDE PHOTOGRAPHIC EMULSION CROSS REFERENCE TO RELATED APPLICATIONS This application is a continuation-in-part application of Ser. No. 18,622 filed Mar. 11, 1970, now abandoned.

This invention relates to a light-sensitive silver halide photographic emulsion containing a combination of spectral sensitizing dyes. More particularly, the invention is concerned with a green-sensitive supersensitizer comprising a monomethinecyanine dye and a benzimidazolocarbocyanine dye.

A silver halide photographic emulsion has an inherent light-sensitive wavelength region. This wavelength region, however, is ordinarily limited to the short wave'- length region of ultraviolet light or blue light. .When such silver halide emulsion is incorporated with a sensitizing dye, the emulsion is broadened in light-sensitive wavelength region and thus can be sensitized. Further, it is well known that when a mixture of a spectral sensitizing dye with other spectral sensitizing dye or with an organic compound is added to a silver halide emulsion, the emsulsion is sensitized to more than the total sum of the effects of the individual compounds. This phenomenon is termed supersensitization, and is detailed in, for example, C.E.K. Mees: The Theory of the Photographic Process, 2nd. Edition, 1954, New York, page 474. I

When subjected to development treatment, a photographic film or paper prepared by use of a greensensitive silver halide photographic emulsion containing a conventional supersensitizing composition has tended to bring about yellow color stain of magenta color. This tendency is particularly marked when the emulsion'contains a gelatine coagulant.

Further, the use of a certain known supersensitizing composition gives a light sensitive material which, when stored at high temperature and high humidity, brings about a decrease of photographic gamma. This is ascribable to the fog formed in the emulsion layer during storage of the light-sensitive photographic material. Even if the proportions of the dyes in said supersensitizer are varied so as to prevent the decrease of photographic gamma, the light-sensitive photographic material is undesirably varied in sensitization maximum to bring about a decrease of green sensitivity.

An object of the present invention is to provide a supersensitizer having stable green-sensitivity even at high temperature and high humidity which has overcome the above-mentioned drawbacks of conventional supersensitizers and which does not bring about any dye contamination in the resulting film after treatment.

Another object of the invention is to provide a lightsensitive silver halide photographic emulsion having high green sensitivity (high speed to green light), which emulsion is less in generation of optical fog even when handled under a safety light having a wavelength of more than 600 mu.

The above objects of the present invention are accomplished by the use of a combination of at least one of the monomethinecyanine dyes of the general formula (1) shown below and at least one of the benzimidazolocarbocyanine dyes of the general formula (II) also shown below. General formula (I):

wherein R}, and R are individually a lower alkyl group or a substituted alkyl group, R and R are individually a lower alkyl group, a hydroxyalkyl group, a sulfoalkyl group or a derivative of any of said groups, Y, and Y are individually a n-propyl, iso-propyl, n-butyl, isobutyl or phenyl group, X is a negative group, and n is l or 2.

All the spectral sensitizing dyes or the abovementioned general formulas are ortho type spectral sensitizing dyes, and the sensitizing dyes of the general formula (I) are green-sensitizing dyes showing a maximum wavelength of color sensitization within a short wavelength region of 500 my. to 550 mu, while those of the general formula ([I) are green-sensitizing dyes showing color sensitization maximum at a long wavelength region of 570 my. to 580 mu. When used singly, therefore, these sensitizing dyes cannot give greensensitive silver halide photographic emulsions the color.

sensitivity of which has been sufficiently broadened in wavelength region. 1

As the result of extensive studies, we have found that I when the spectral sensitizing dyes of the general formulas (I) and (II) are used in combination'gwith each other, there is attained marked green-sensitization due to the synergistic effect of said spectral sensitizing dyes. That is, when a combination of said two kinds of spectral sensitizing dyes is added to a silver halide photographic emulsion, the emulsion is sensitized in short wavelength portion and long wavelength portion of the green light-sensitive spectral zone, whereby there are attained not only high speed green-sensitivity but also green sensitization having a new spectral sensitization maximum which cannot be attained when these spectral sensitizing dyes are used singly. Further, the combination of the two spectral sensitizing dyes has such excellent characteristics that it has no detrimental interactions with other photographic additives and does not leave any residual color stain on a photographic film after development.

The sensitizing dyes of the general formula (I) are synthesized by use of quaternary 2-alkylmercaptoquinolium salts, and those of the general formula (ll) are obtained according to the methods described in Q 5 13% No. 3,268,334.

3 Typical examples of the spectral sensitizing dyes represented by the general formulas (I) and (Il) are shown below, but it is needless to say that compounds usable in the present invention are not limited only to these. Typical examples of the spectral sensitizing dyes 5 CH: of the general formula (I): om ocnr-oncmsor (1) /1 Se W mm a i H 5 I N CH O CH 8 v l CH: +N

l GH- cums-03- N 2 7 431K; *N

fim Se W g lp mfibflzlq ai CH- M Q n a s 2 5 i I (CHmCOOH I- \N CH-\ CH 3 (3) A 86- Ahm- +N l M CH; ,P I Typlcal examples of the sensltlzmg dyes represented by (CH:):O(CH:);SO;- the general formula (ll):

=YCHCH=CH (1131101000 0006311101) N N a no mP FB dense:

-=oH-cH=CH (19110040 0 C CO 0 Cam) N H N o a J1EE: I:

(9) (EH5 231s I I=CHCH=CH- (I1)HQC400C I COOCCEKII) N u mm wflmsom H:): H2)a a' V l C a 1 =CHCH=CH Y 94 V a HnhSOr 1 1 cm owmnbn (CH:)aO(CH,),0H

v vIII N C H- CH=C H- (n)H C;00C COOCgHKIl) (12) (EH5 01H;

XSZHDAEQL The supersensitizers according to the present invention have such excellent characteristics as mentioned previously and can impart ideal green-sensitivity to silver halide photographic emulsions. Accordingly, the super-sensitizers of the present invention are highly ef-- fective as color sensitizers not only for green-sensitive emulsions for high speed, light-sensitive. black-andwhite photographic materials but also for. greensensitive emulsions for light-sensitive color photographic materials.

The silver halide photographic emulsions in accordance with the present invention can be varied in distribution of spectral sensitization maximum wavelengths by varying the kind and amount of the spectral sensitizing dyes of the aforesaid general formulas. These sensitizing dyes may be added to silver halide photographic emulsions after dissolving them, either singly or in admixture, in a water miscible organic solvent such as methanol, ethanol or the like. Further, the spectral sensitizing dyes may be added to the emulsions at any time during preparation of the emulsions, but are preferably ing, in general. The amounts of the spectral sensitizing dyes to be added vary depending on the kind of silver halide emulsions, but are ordinarily within such a wide range that the total amount of the spectral sensitizing dyes of the formulas (I) and (II) is 1 mg. to 200 mg. per Kg. of the emulsion. In this case, the ratio of the dye of the formula (I) to that of the formula (ll) is preferably sensitized with noble metal sensitizers, sulfur sensitizers, reduction sensitizers or polyalkylene oxide type sensitizers. Further, the emulsions may have been incorporated according to known procedures with such additives as stabilizers, surface active agents and hardadded immediately after completion of second ripeneners.

In the above-mentioned color sensitization process of the present invention, other carbocyanine or merocyanine dyes may be additionally used to provide high speed spectral sensitivity, so that it is possible to carry out easily spectral sensitization for light-sensitive black-and-white photographic materials using various silver halides.

The present invention is illustrated in further detail below with reference to examples.

EXAMPLE 1 A silver iodobromide emulsion containing 3 mole percent of silver iodide which had been treated with a gelatine coagulant was subjected to second ripening following sensitization with gold and sulfur, thereby to prepare a neutral emulsion for high speed negatives. To.

1 Kg. of this emulsion was added, either singly or in admixture in such amount as shown in Table l, 0.1 percent methanol solutions of the spectral sensitizing dyes of the aforesaid general formulas (I) and (II). The emulsion was allowed to stand with stirring at about 40C. for minutes, the spectrally sensitized emulsion thus obtained was then coated on a film base, followed by drying, to obtain a green-sensitive photographic material. For the purpose of sensitometry, the thus obtained photographic material was exposed to light through a yellow light filter by means of a sensitometer KS-l (manufactured and sold by Konishiroku Photo Industry Co., Ltd.) at 100 Lux and at 5,400K, developed at 20C. for 5 minutes with a developing solution of the composition shown below, and subjected to fixing, water-washing and drying.

Developing solution:

Metol (N-methyl-p-aminophenol sulfate) Anhydrous sodium sulfite Hydroquinone Sodium carbonate (monohydrate) 29 Potassium bromide Water to make 2 liters not injure the photographic properties thereof and make the emsulsions less in color stain (residual color) on the films after development.

The accompanying drawings FIGS. I and 2 are spectral sensitivity curves. In FIG. 1, the curve (a) shows the spectral sensitivity curve of a photographic material using the silver iodobromide emulsion prepared in Example and the curves (b) and (c) show, respectively, the spectral sensitivity curves of the Samples 1 and 2 obtained in Example 1. In FIG. 2, the curve (d) shows the spectral sensitivity curve of the Sample 3 obtained in Example 1. From these drawings also, it is understood that the photographic emulsions according to thepresent invention have excellent photographic properties.

EXAMPLE 2 To an l-Iigh speed silver 'indobrorriide emulsion prepared according to an ordinary process were added, in such combinations and amounts as shown in Table J; 2H5 III C'Ha I (B) CzHs 02114 =OHCH=OH o1 ('3 (E2115 Each of the thus obtained samples wassubjected to storage test at high temperature and high humidity to obtain such results as shown inTable 2. I

TABLE 1 r ount Spectral sensitizing dye added Relative Spectral (0.1% cc./ speed to Residual sensitivity I Exemplifl- General kg. emulyellow color maximum Sample No. cation No. formula sion) light stain (my) [I] O. 06 [II] 60 0. 07 [Hi-[II] 4U+20 210 0. 04 570 5O 95 0. 07 13) [II] 60 160 0. 06 [I]+ [II] 35+25 205 0. 04 575 3) [I] 60 80 0. 06 [II] 60 150 0. 06 [II-l-[II] 40+20 0. 03 570 ples, .the spectral sensitivity of the resulting photographic materials, and that even when added to emulsions prepared by use of a gelatinecoagulant, they do The exposure, development Enid sensitometry in this example were effected in the same manner as in Example l, and the sensitivity value in the table was represented b y a relative sensitivity based on than? thecon trol sample.

TABLE 2 Alter incubation for 3 days Immediately after preparation at 50 0.. RH 80% Amount added Relative Relative (co/kg. speed to speed to Sample N o. sensitizing dye emulsion) yellow light Gamma Fog yellow light Gamma Fog 1 (2; plus (8) 40+20 130 0. 74 0. 04 130 0. 72 0. 05 35+25 110 0. 71 0. 04 115 0. 73 O. 05 40+20 125 0.73 0. 06 125 0. 72 0.06 30-1-30 120 0. 70 0. 05 110 0. 70 U. 05 14 c tr l (A) plus (B) 40+20 100 0.72 0.07 95 0.65 0.08

F7651 Table 2, it is evident th at even when stored under severe conditions, the light-sensitive materials 10, ll, 12 and 13 according to the present invention are less in formation of fog and can display excellent photographic properties without degradation of photographic sensitivity and gamma.

" EXKMPLE 3 A high speed silver iodobromide emulsion, which had been second ripened to the optimum sensitivity after gold and sulfur sensitization, was divided into 3 portions. To 1 Kg. of each divided portion of the emulsion were added, in such combinations as shown in Table 3, the spectral sensitizing dyes of the aforesaid general formulas (l) and (II). For comparison, the same control sample as in Example 2 was used. Each of the thus treated emulsions was allowed to stand with stirring at 40C. for about 20 minutes. Thereafter, the thus spectrally sensitized emulsion was charged with a hardener and a coating aid and then coated on a film base, followed by drying, to prepare a sample.

In order to test each of the thus prepared samples in optical fog formation under red light, the sample was continuously irradiated, through a filter (Sakura No. 4-A) capable of transmitting a light of more than 600 my, in wavelength, with a light positioned at a distance of 100 cm. from the sample (the light source used was an incandescent lamp of 100V-20W).

After irradiation, the samples were developed in the same manner as in Example 1 and then measured in fog density to obtain the results as shown in Table 3.

The results of sensitometry effected in the same manner as in Example 1 were also set forth in Table 3.

advantageously less in optical fog formation under red light.

Experiment 4 A silver iodobromide emulsion containing 3 mole percent of silver iodide which had been treated with a gelatine coagulant was subjected to second ripening following sensitization with gold and sulfur, thereby to prepare a neutral emulsion for high speed negative. To 1 of this emulsion was added, either singly or in ad mixture in such amount as indicated in Table 1 below, 0.1 percent methanol solutions of the sensitizing dyes represented by the general formulas (I) and (II) of the present specification. For comparison, a compound set forth in claim 10 of U.S. Pat. No. 3,268,334 was similarly used to prepare a control sample.

The emulsions were allowed to stand with stirring at about 40C. for 20 minutes to complete colour sensitization. The sensitized emulsions were then coated on a film base and dried to prepare green-sensitive photographic materials. The sensitive photographic materials were exposed through a yellow light filter in accordance with the method 118 1604-K, developed at 20C. for 5 minutes with a developing solution described in the specification, fixed, washed with water, dried and subjected to sensitometry. The results obtained were shown in Table 1 below. in the table, the sensitivity value is represented by a relative value, rating as the yellow sensitivity of a photographic film added with the following sensitizing dye (1) according to the present invention in the amount of 60 mg. per Kg. of the emulsion. The residual color stain is a density measured by means of a color densitometer.

Dyes According to the Present Invention TABLE 3 Red light irradiation time Amount added 0min. 10 min. 20 min. Relative (0.1% speed to Samp ceJkg. Optical Optical Optical yellow No. sensitizing dyes emulsion) fog fog fog light 30+20 0. 06 0. 07- 0. 09 17 plus (13 30+20 0.05 0.06 0.07 18 Control (A) plus (B) 30+20 0.05 0.10 0.15 100 For Comparison (U.S. Pat. No. 3,268,334) ye 4) 01H; C1115 Control dye (Example 9 of U.S. Pat. No. 3,268,334)

C Hg 02 (iSO) CH-CH=CH 1!: C O O C3H1USO) N @N CH=CHCH 1 11503000 COOCBHS 135 gHs 1 2H5 2 5 1e 1 O TA 4 For Comparison 1x1 1 1333; Relative Control dye (Example 7 of U.S. Pat. No. 3,268,334)

(0.1% speed to Residual mL/kg. yellow color sensitizing dye added emulsion) light stain Dye (1) 60 190 0.06 V Dye (8) 60 0 0-07 (3H5 (lhHs 4o+20 210 0. 04 N N $8 :22 j so 170 01 O6 OH=CHCH 70 180 0. 07 11501000 01 N N Dye (1) plus control dye (Exp. 9)

5 art 20 190 0 or! es wise 185 o 08 1313! 9 TABLE 5 Immediately after After incubation for 3 Azgdogig preparatlon days at 0., RH

(0.1% Relative Relative ml. /kg. speed to speed to sensitizing dye added emulsion) yellow light Gamma. yellow light Gamma Dye 1 plus Dye (14) 40+20 100 0.04 100 0. Presentmmmn s" Ely-'1 "fiifi' iiv 23133 33 iii ye p us con to xam 80 ()7 The radium Table i clearly show that a combina- The results in Table 5 clearly show that even when tion of dyes (1 and (8) according to the present invenstored under severe conditions, the combination of tion shows excellent yellow light sensitivity, whereas a dyes (1) and (14) according to the present invention is control [dye (l) ricontrol dye (Exp. 9)] shows less less in formation of fog and can display excellent phosynergistic effect by combination and more residual 40 tographic characteristics without lowering of a yellow color stain. light sensitivity.

Experiment 5 We claim:

Following the same procedure as described in Exper- A f Silver halide Photographic emu! iment 4, a combination of dyes indi at d i T bl 2 slon which comprises at least one spectral sensitizing below was added to a silver iodobromide emulsion, fol- 45 y l'epresamed y the general formula lowed by a suitable amount of 4hydroxy-6-methyll,3,3a,7-tetrazaindene as a stabilizer. The emulsion *w W was coated on a film base and dried to prepare a green- Z sensitive photographic material. W; I

Each of the samples thus obtained was subjected to 50 \N H W1 storage test at high temperature and high humidity. The results obtained were shown in Table 5 below. N

Exposure, development and sensitometry in Experia -hm ment 2 were carried out in the same manner as in Experiment 4. In the table, the sensitivity value was repre- 55 wherein R is a lower alkyl group, R is a sulfoalkyl sented in terms of a relative sensitivity by rating as group or a carboxyalkyl group, W and W are individuthe yellow sensitivity immediately after preparation of ally a hydrogen atom or a lower alkyl group, Z is a sul-. a combination of dyes (l) and (14) according to the fur or selenium atom, X is a negative group, and n is present invention. 1 or 2, in combination with at least one spectral sensi- Dyes According to the Present Invention tizing dye of the general formula W R8 I i l CHa N (demot R5 in (Km-1 wherein R; and R are individually a lower alkyl group, a hydroxyalkoxyalkyl group or methoxycarbonylalkoxyalkyl group, R and R are individually a lower alkyl *group, a hydroxyalkyl group or a sulfoalkyl group, Y

and Y are individually a n-propyl, iso-propyl, n-butyl, iso-butyl or phenyl group, X" is a negative group, and n is 1 or 2. 

2. A light-sensitive silver halide photographic emulsion as claimed in claim 1, said emulsion being a color photographic emulsion.
 3. A light-sensitive silver halide photographic emulsion as claimed in claim 1, further comprising at least one magenta coupler. 